JPH0318058Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a welding nozzle used for electric welding of metals.

[Conventional technology]

A welding nozzle is an accessory part that is attached to the tip of a torch to provide a gas shield function when performing electric arc welding in an inert gas atmosphere.The welding nozzle is generally made of metal based on copper or iron. has been done. However, this type of metal nozzle has the disadvantage that spatters scattered during welding tend to adhere to it. The accumulation of spatter on the nozzle surface not only impairs the gas shielding effect but also impedes arc safety and welding wire delivery, making it necessary to perform frequent scraping operations in a short period of time. For this reason, it is a major cause of lowering work efficiency even in the field of automatic welding, which has seen remarkable progress in recent years.

In order to avoid this phenomenon, a method has been proposed in which a coating agent is applied to the nozzle surface to prevent the adhesion of spatter, but this method has not been sufficiently effective.

Carbon materials have recently been attracting attention as nozzle materials. Carbon materials have excellent self-lubricating properties and unique characteristics that make them difficult to get wet with molten metal, so they essentially have material functions that effectively prevent spatter adhesion.

However, carbon materials have one drawback of low material strength and oxidation resistance. For this reason, there are problems such as damage due to mechanical or thermal shock during welding work, or oxidative wear due to contact of the tip of the nozzle with accumulated heat with a small amount of intervening air.

[Problem that the invention attempts to solve]

This idea solves the above problems and creates a welding nozzle with a material structure that has excellent spatter adhesion prevention properties even when used continuously for a long period of time, and does not suffer from deterioration phenomena such as breakage and oxidative wear. This is what we provide.

[Means for solving problems, examples]

That is, the welding nozzle according to this invention is configured such that a silicon carbide coating layer is formed on the surface of a carbonaceous master base material by a conversion method, and the silicon carbide coating layer at the tip of the nozzle is mirror-polished. The above characteristics.

To explain based on the illustrated embodiment, 1 is a carbonaceous original base material, and 2 is a silicon carbide coating layer. The carbonaceous prototype base material 1 is formed by molding carbon or graphite material in advance so as to match the shape and dimensions of a nozzle having a predetermined connecting threaded portion 3 . Since carbonaceous materials are extremely easy to process, they can be easily formed into desired shapes and dimensions by machining.

Silicon carbide coating layer 2 is formed by a conversion method. The conversion method is a method in which silicon monoxide gas is brought into contact with the carbonaceous original base material 1, and SiO+2C
→This is a method of converting the surface into silicon carbide through an interfacial reaction between SiC and CO. In this coating method, the carbonaceous original substrate 1 is placed in isolation in a reaction heating furnace charged with silicon dioxide powder or a reactant mixture consisting of silicon dioxide powder and carbon powder, and the inside of the furnace is kept inert. This is done by raising the temperature to over 1800℃ while maintaining the atmosphere. Through this process, silicon monoxide gas generated from the reactant mixture comes into contact with the carbonaceous original substrate to gradually form a silicon carbide coating layer, but the process proceeds through a mechanism in which the substrate carbon itself participates in the reaction. Therefore, the formed coating layer is extremely strong and dense, and variations in shape and dimensions are always within ±0.1 mm, ensuring a high degree of dimensional accuracy.

As a means of forming a silicon carbide coating layer on a carbonaceous material, a method is known in which silicon carbide is directly deposited by thermally decomposing an organosilicon compound containing hydrocarbons. Unlike the convergence method, this method cannot stably form a silicon carbide layer with high dimensional accuracy, and layer peeling occurs during use, so it cannot be applied to this purpose.

The silicon carbide coating layer 2 formed by the conversion method has a dense and smooth surface and has the function of preventing spatter adhesion even in its original state, but it is necessary to mirror-polish the inner and outer surfaces of the tip portion 4. The anti-adhesion function can be significantly increased.

[Functions and effects of the invention]

Since the welding nozzle of this invention has the above-mentioned material structure, the following highly practical effects are brought about.

(1) Since the entire surface of the carbonaceous prototype base material is firmly and integrally coated and bonded with the silicon carbide layer, the material strength and oxidation resistance are greatly improved. This effectively reduces the occurrence of damage to the nozzle due to mechanical or thermal shock during welding work, and also prevents air from coming into contact with the heat storage tip due to leakage from the connection thread or other reasons. Even if such phenomena occur, wear and deterioration due to oxidation does not occur at all.

(2) Since the silicon carbide coating layer is formed by the convergence method and the silicon carbide layer at the tip of the nozzle is mirror-polished, it is possible to almost completely prevent the accumulation of spatter. In addition, the high dimensional accuracy of layer formation eliminates the need for secondary processing such as connection threads, contributing to improved manufacturing efficiency.

(3) Since the base material is made of carbonaceous material, it is lighter than metal nozzles.

(4) Due to the above-mentioned improved performance imparting effects, long-term continuous use is possible regardless of automatic welding or semi-automatic welding. Therefore, welding efficiency is significantly improved.

[Brief explanation of drawings]

The figure is a partially cutaway vertical sectional view illustrating the welding nozzle of this invention. 1... Carbonaceous original base material, 2... Silicon carbide coating layer, 3... Connecting screw portion, 4... Mirror polished nozzle tip portion.

Claims (1)

[Scope of utility model registration request] A welding nozzle in which a silicon carbide coating layer is formed by a conversion method on the surface of a carbonaceous prototype base material, and the silicon carbide coating layer at the tip of the nozzle is mirror polished.